The dendrite growth, morphology control and deposition properties of uranium electrorefining

Abstract

In the widely researched and demonstrated molten salt-based electrorefining process, it is extremely important to control the morphology and growth of uranium dendritic in order to guide the design, operation, safeguard and even upgrade of industrial equipment. Herein this work focuses on the influences of various electrochemical techniques and cathode materials on the dendrite growth and deposition performance for uranium electrorefining. The corresponding current efficiency, deposition rate, deposit compactness, dendrite size distribution and growth rate were studied and compared. It was found that the electrode material has limited effects on the current efficiency, whilst the deposition rate of uranium and growth rate of dendrites on inert cathodes (W and Mo) are relatively higher than that on active cathodes such as stainless steel, Ni and graphite. For controlled current techniques, both the uranium deposition rate and dendrite growth rate are linearly related to the current density. For the controlled potential techniques, only the uranium deposition rate has a linear relationship with the overpotential, whilst the dendrite growth rate has a power exponential relationship with the overpotential. Regardless of the electrolysis technique, controlling the growth of uranium dendrites will sacrifice the deposition rate. In addition, the pulse potential technique can exponentially reduce the growth rate of uranium dendrite at the expense of 30–40% deposition rate.